Manufacturing tetraethyl lead



Patented July 18, 1950 UNITEDZ- sures; m;

MANUr crURmGi'rETRAnTmL LEAD...

Willis Jackson'Clem;--Wilmington;- Del.,ands'Royt-.. Joseph-Plunkettg =Woodstown, N; J3, assignors" to Irdu-zPont :-de Nemurs;;&Company; W 1- mington,pel a corporation of Delaware NnDrawirrg; Application Marclr29, 19516, ,7 SerialNo. 658.228

8 claim-a (01. 26,04-37-)i This invention relates tota -process:forxmanuf acturing tetraethyl leadand 4 more particularly to catalyzing the ethylation of lead monosodium.v alloywith ethyl chloride.

In the usual commerciaLprocess-for manuface. turingtetraethyl .lead, ethyl chloride 1 is reacted with lead monosodium alloy in: a closed vessel under pressure at about 65 Cato-about 85 =.C. This process orcl-inarily-requiresor -more hours to complete -the-reaction. In recent years, it has become important to very-greatly increase a theproductionof-- tetraethylleads: Inorder ;,to increase such production 'materiallyi it has-become l. important and desirable to greatly decrease the timefor carrying. the reaction to :completion.

When it has been-attempted to decrease "the time. of reaction in-the old-processes; the yield oftetraethyldeadirom a, given batch of alloy is--ma-- terially -decreased --and additional and: difiicul-t problems of separating the tetraeth-yl'lead fromthe reaction'mass have been encountered.-

An object oi the present invention-is 1 to provide a proces whereby the speed-of --the reaction--is materially increased without-a substantial de crease-in the-yield} Another objectistoprovide- 25 a process whereby the time iortcompletion-of--thereaction may be greatlydecreasedwith a-resulting-large-increasein the production of tetraethyl lead. I A further object is to provide new and-improved *catalysts for the reaction ofethyl-ch10:- 3Q 1 ride with lead 'monosodium alloy-l Other objects are to advancethearte .Still other objects will-- appear hereinafter The above and other objects may be accomplishedin accordance with-"our invention which comprises carrying out the reaction of ethyl chloride on lead monosodium alloy, in the presence of a small proportion, sufficient to accelerate the reaction,;of an aldehyde which contains from 0 to 1 benzene rings and consists .ofcarbon, hydro-1 gen, oxygen and 0 to 2 halogen atoms, the oxygen being aldehyde and ethereal oxygen solely. We have iound that such aldehydes are extremely, effective catalyst for thisreaction increasing the speediqf the reaction tosuch an extent thatnthe 4.5

time required for completion ofthe reaction is reducedwtoabout one hour. At the same time, high yields of tetraethyl lead are obtained and the difficulty of separating'the tetraethyl lead from thereaction mass is not increased. There- '50 1 by, the-productionof tetraethyl lead in e -plant is very materially speeded and increased.

We have found that the members of the above defined class of aldehydes are, as a whole, very efiective for accelerating the reaction.

The aldehy de' may be aromatic, alicyclic or acyclic; but, preferably is' aliphatic. The term aliphatic 'as employed hereinis employed in thestrict sense to mean'an open chain and to exclude aromatic and li-ke substituents. The aliphatic aldehydes may be saturated or unsaturated and may contain halogen andether groups as-substituents. The term aldehyde oxygen will be understood to mean the oxygen atom which formsthe aldehyde-group. The term ethereal oxygen will be understood tomean the oxygen of anether group; Preferably, the oxygen in the aldehydes will" be aldehyde oxygen solely.

Aldehydes which-have been foundto be effec tlve=-to accelerate this reaction are asfollows':

The amount ofthe aldehyde employed maybe varied widely and will depend upon the conditions' employed and particularly on the size of the batches and the equipment. Generally, they will be employed in the proportion of from about 0.1%'-toabout 2% based on the ethyl chloride. If proportion of aldehyde substantially above 2% are employed in large scale plant operations carried'out in an autoclave, they become less effective and may even be detrimental to the yields. 7 Generally, in small scale production in a bomb, larger proportions of the aldehydes will beefiectlve and may even be-desirable. In small scale experiments; some of the aldehydes have been-found to be most effective'in proportions ofabout 1%, based on the ethyl chloride. However, in substantially all plant operations, the optimum results will be obtained with less than 1% oi the aldehyde.

While the aldehyde may be added to the reactants or to the reaction vessel in any desired manner and at any desired stage of the process, it will generally be most desirable to add the aldehyde to the ethy1 chloride prior to mixing the ethyl chloride with the alloy. The process of making tetraethyl lead will remain unchanged, except for the addition of the aldehyde and the shorter time required for the completion of the process.

In order to more clearly illustrate our invention, preferred modes of carrying the same into efiect and the advantageous results to be obtained thereby, the following examples are given:

EXAMPLE I Approximate 100 g. of lead-sodium alloy (containing 10.0% sodium) of a size which passed a4 mesh screen and was retained on a mesh screen, was charged into each of six steel bombs having a capacity of 150 ml. Fifty milliliters of ethyl chloride was added to each bomb and 0.2? cc. of acetaldehyde was added to each of three of them. The bombs were closed and tumbled in a water-bath maintained at 85 C. for 90 minutes. After the heating period, the hot water was drained and the bath was refilled with cold water. After minutes, the bombs were removed and placed on ice.

Each reaction mass was extracted with 2000 m1. of benzene. A 50 ml. aliquot of the benzene solution was titrated with iodine solution to determine the yield of tetraethyl lead. The yields, in the three bombs containing acetaldehyde, were 78.93%, 83.67% and 82.58% While the yields in the other three were 77.36%, 77.82% and 79.24%.

In another series of tests employing 50 g. of lead monsodium alloy and 100 g. of ethyl chloride and various aldehydes in different concentrations, a heating time or only five minutes was used in order to show more clearly the acceleratin'g efiect. The results are given in the following Table I in yield of tetraethyl lead:

Table I Accelerator 0. 1% 0. 2% 0. 5% l. 0%

None (control). 14. 51 i-Bntyraldehyde--- 31.90 35. 94 43.01 55. 84 n-Butyraldchyde 47.41 57.17 60.25 a-Ethyl-B-n-propy1acrolein 18.94 28.56 50. 70 59.27 a-n-Amylcinnama1dehyde. 28.91 30. 51 42. 77 53.80 Benz-aldehyde 18.40 20.82 45.18 51.08 Phenylacetaldehyde 26.60 32.86 45.19 50.50

4 by the reaction of ethyl chloride on lead monosodium alloy, the improvement which comprises carrying out the reaction in the presence of a small proportion, sufiicient to accelerate the reaction, of an aliphatic aldehyde which, except for the oxygen of the aldehyde group, consists of carbon and hydrogen.

3. In the process of making tetraethyl lead by the reaction of ethyl chloride on lead monocarrying out the reaction in the presence of a sodium alloy, the improvement which comprises 1 carrying out the reaction in the presence of a small proportion, sufficient to accelerate the re-- action, of an aliphatic aldehyde which consists small proportion, sufiicient to accelerate the reaction, of an aldehyde which contains a single benzene ring and consists of carbon, hydrogen and aldehyde oxygen solely.

5. In the process of making tetraethyl lead by the reaction of ethyl chloride on lead monosodium alloy, the improvement which comprises carrying out the reaction in the presence of a small proportion, sufficient to accelerate the reaction, of butyraldehyde having the empirical formula Cal-ECHO.

6. In the process of making tetraethyl lead by the reaction of ethyl chloride on lead monosodium alloy, the improvement which comprises carrying out the reaction in the presence of a small proportion, sufiicient to accelerate the reaction, of n-butyraldehyde.

'1. In the process of making tetraethyl lead by the reaction of ethyl chloride on lead monosodium alloy, the improvement which comprises carrying out the reaction in the presence of a small proportion, sufficientto accelerate the reaction, of benzaldehyde.

8. In the process of making tetraethyl lead by the reaction of ethyl chloride on lead monosodium alloy, the improvement which comprises carrying out the reaction in the presence of a small proportion, sufficient to accelerate the reaction, of an aldehyde of the class consisting of aliphatic aldehydes which consist of carbon, hydrogen and oxygen, the oxygen being aldehyde and acylic ethereal oxygen solely, aromatic aldehydes which contain a single benzene ring and consist of carbon, hydrogen and aldehyde oxygen solely and corresponding chlorinated aldehydes containing from 1 to;2 chlorine atoms solely.

WILLIS JACKSON CLEM. ROY JOSEPH PLUNKETT.

REFERENCES CITED The following references are of record in the Great Britain Feb. 16, 1925 

1. IN THE PROCESS OF MAKING TETRAETHYL LEAD BY THE REACTION OF ETHYL CHLORIDE ON LEAD MONOSODIUM ALLOY, THE IMPROVEMENT WHICH COMPRISES CARRYING OUT THE REACTION IN THE PRESENCE OF A SMALL PROPORTION, SUFFICIENT TO ACCELERATE THE REACTION, OF AN ALIPHATIC ALDEHYDE WHICH CONSISTS OF CARBON, HYDROGEN AND OXYGEN, THE OXYGEN BEING ALDEHYDE AND ACYLIC ETHEREAL OXYGEN SOLELY. 